Unit of Plant Physiology, Department of Plant Biology, Faculty of Biology, University of Barcelona, Diagonal 643, 08028 Barcelona, Spain.
Cell Biol Toxicol. 2012 Feb;28(1):57-68. doi: 10.1007/s10565-011-9205-7. Epub 2011 Oct 19.
Chromium pollution of freshwater is hazardous for humans and other organisms, and places a limitation on the use of polluted water sources. Phytoremediation, the use of plants to remove pollutants from the environment, is a cost-effective, environmentally friendly approach for water decontamination. To improve the efficiency of the process, it is essential to increase the current knowledge about Cr accumulation in macrophytes. Plants of Iris pseudacorus L. were treated with Cr(III) at 0.75 mM for 5 weeks to investigate Cr localization by means of transmission electron microscopy and energy dispersive X-ray analysis. Chromium induced severe ultrastructural alterations in the rhizodermis (cell wall disorganisation, thickening, plasmolysis, and electron-dense inclusions) and rhizome parenchyma (reduced cell size, cell wall detachment, vacuolation, and opaque granules). The highest Cr contents were found in the cell walls of the cortex in the roots and in the cytoplasm and intercellular spaces of the rhizome. The Cr concentration in root tissues was in the order cortex>rhizodermis>stele, whereas in the rhizome, Cr was evenly distributed. It is proposed that root and rhizome have distinct functions in the response of I. pseudacorus to Cr. The rhizodermis limits Cr uptake by means of Si deposition and cell wall thickening. The rhizome cortex generates vacuoles and granules where Cr co-occurs with S, indicating Cr sequestration by metal-binding proteins.
淡水的铬污染对人类和其他生物是有害的，并限制了受污染水源的使用。植物修复，即利用植物从环境中去除污染物，是一种具有成本效益且环保的水净化方法。为了提高处理效率，必须增加当前关于大型植物中铬积累的知识。用 0.75mM 的 Cr(III) 处理鸢尾属植物 5 周，通过透射电子显微镜和能量色散 X 射线分析研究 Cr 的定位。铬诱导了根皮层（细胞壁组织紊乱、增厚、质壁分离和电子致密内含物）和根茎薄壁组织（细胞体积减小、细胞壁脱落、液泡化和不透明颗粒）的严重超微结构改变。在根的皮层和根茎的细胞质和细胞间隙中发现了最高的 Cr 含量。根组织中的 Cr 浓度顺序为皮层>根皮层>中柱，而在根茎中，Cr 分布均匀。据推测，根和根茎在鸢尾属植物对 Cr 的反应中具有不同的功能。根皮层通过硅沉积和细胞壁增厚来限制 Cr 的吸收。根茎皮层产生液泡和颗粒，Cr 与 S 共同存在，表明 Cr 被金属结合蛋白螯合。
